Skip to main content

Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"

See other formats



hydrochloric acicl and 5 c.c. of cone, nitric acid, and subsequently diluted
with water, allowed to cool, made up to volume and filtered.

To 25 c.c. of the filtrate (== 0-5 gram of substance), or 50 e.c. (== i gram)
with a poor phosphate, are added 20 c.c. of the ammonium citrate, 50 c.c. of
water, 50 c.c. of ammonia (D 0-92) and 50 c.c. of magnesia, mixture, the
whole being then stirred vigorously without the stirrer touching the walls
of the vessel. After being stirred continuously for 30 minutes with a mechan-
ical stirrer or, if this is not. available, after standing for at least 5......6 hours,,

the liquid is filtered and the precipitate washed, first by deeantation and
then on the filter with ammonia (i vol. of ammonia of J) -=0-96 and 3
vols. of water) until the wash liquor is free from chloride. The filter is then
dried at 100, the. precipitate detached, tin; filter-paper burnt separately and
precipitate and filter-ash healed together in a platinum crucible until of
constant weight. The weight of magnesium pyrophosphate thus obtained,
multiplied by 128 when 0-5 gram of substance was taken or by 04 for i
grain, gives directly the amount of phosphoric anhydride (l'./^) per TOO
grams of substance, the results being always expressed in this [onn.

Menozzi's modification   (iHo.8)   of IVmherton's  volumetric
included among the Italian oflidal methods.

method in also

5. Determination of the Potash

From 5 to 10 grams of substance ' are healed to boiling with 200-250
c.c. of water and 5 -.10 c.c. of cone, hydrochloric acid in a 500 e.e. measuring
flask. When cool, the liquid is made up to volume and mixed, 100 e.c. of
the solution (i--2 grams of substance) being then transferred to another
500 c.c. llask and boiled. At this point, if the material is rich in sulphate,
barium chloride solution is added until no further precipitation occurs and
then slight excess of baryta, water (plienolphthaleiii being added to the liquid,
the baryta is added until the solution turns reel) ; if the material is poor in,
or free from, sulphate, baryta solution alone is added. When cold, the
liquid is made up to volume, shaken, and filtered through a. dry filter, 250 c.c,
of the filtrate (0-5-i of substance) being introduced into another 500
c.c. llask ami boiled. Ammonium carbonate solution is then gradually
added, with constant agitation, as long as precipitate is formed, the llask
being heated for some time on a steam-hath in order that, the precipitated
barium carbonate may become, crystalline, When cold, the volume1 is made
up and the liquid shaken and filtered,'"

1 With complex organic fertilisers, HI -jo ^nuiis (according to the supposed tiehuesK
in potash) arc diarml in a platinum dish at a red heat, the mass being extracted with
water and cone., hydrochloric arid and the liquid evaporated to dryness, The residue
is heated at 120", dissolved in dilute hydrochloric, acid, tranMferred to a 500 c.c, llask,
made up to volume and mixed. An aliquot: part of the liquid is then treated with
barium chloride, baryta, etc,., in the ordinary way.

8 With potassium chloride or sulphate, the treatment, with barium e.hloride, baryta
water and ammonium carbonate may be made .successively in the original llask iu
which the substance (5 grams) is dissolved, the volume being then made up and the
liquid shaken and filtered, 23 c.c, of the Idtratc ( ; 0-45 gram of substance) being then
taken. At this dilution the volume occupied by the precipitate is without appreciable
inlluence.      l.2o